1. Field of the Invention
This invention relates to sheet or plate metal machining equipment such as a turret punch press and laser beam machine which machine sheet or plate workpieces, and more specifically, to an improvement of a work clamp device to hold the edge or end of the workpiece in the sheet or plate material machining equipment.
2. Description of the Prior Art
As a sheet or plate material machining equipment which machines sheet or plate workpieces, the laser beam machine and turret punch press are known. In the laser beam machine, a workpiece is positioned relative to the machining area in X and Y axis directions when the work clamp device holding the edge of the workpiece, and/or a laser machining head is relatively moved. In the turret punch press, the workpiece is positioned relative to the machining area in the X and Y axis directions when the work clamp device is moved in the X and Y axis directions. In either case the work clamp device holding the edge of the workpiece may be machined when it enters the machining area of the sheet or plate material machining equipment.
Therefore, the conventional machines are generally equipped with a detector to detect the entry of the work clamp device into the machining area of the sheet or plate machining equipment so that the operation of the sheet or plate machining equipment is stopped when the detector operates. And when the operation of the sheet or plate machining equipment is stopped, it is necessary for the operator to manually remove the work clamp device from the machining area of the sheet or plate machining equipment. Therefore, once the sheet or plate machining equipment is stopped, it takes a long time before it is restarted.